Tech Report CS-89-25

Plan-Related Negation in Story Understanding

Solomon Eyal Shimony

March 1989


This paper discusses simple uses of negation in story understanding. We show that the meaning of a negated sentence is not simply its logical form, but also indicates an ``expectation'' that its non-negated form would hold. We extend the representation of plans to handle the counterfactual statements needed for negation, by treating plans as objects. We present a theory incorporating the extra meaning into a story-understanding system based on first-order plans. The plan representation introduced here is shown to be useful for understanding stories where agents change their plans, even in stories without negative sentences.

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